Gas-To-Liquid Heat Exchanger and Gas Particulate Scrubber

ABSTRACT

A gas-to-liquid heat exchanger is presented, where a gas is introduced directly to liquid. The liquid is exposed to the gas as a liquid film upon a series of rotating heat exchange surfaces partially submerged in a liquid reservoir. The liquid vaporizes and then re-condenses on subsequent heat exchange surfaces, such that heat is exchanged between the gas and the liquid. Particulates within the gas coalesce into the vaporized liquid and collect into the liquid reservoir as the vapor re-condenses.

FIELD OF THE INVENTION

The present invention relates to heat exchangers, and more particularly,is related to a gas-to-liquid heat exchanger that also has the capacityto handle particulate-laden gas (dirty gas).

BACKGROUND

A heat exchanger transfers heat from one medium to another. Examples ofheat exchangers include gas-to-gas, gas-to-liquid, and liquid-to-liquid.The media may be separated by a solid barrier of a heat conductingmaterial, so that they never mix, or they may be in direct physicalcontact. Heat exchangers are used for space (or process) heating and/orcooling, for example, in power plants, or chemical plants.

Shell and tube heat exchangers consist of a series of tubes. The tubescontain a first fluid to be either heated or cooled. A second fluid runsover the tubes that are being heated or cooled so that the second fluidcan either provide heat to the first fluid or absorb the heat from thefirst fluid as required.

FIG. 1 shows a shell and tube heat exchanger in the context of a priorart pressurized boiler 100. Fuel is burned by a burner 110, and hotexhaust gas from the burner 110 enters an ingress chamber 160 of a watervessel 120 through a burner exhaust vent 115. The water vessel 120 issubstantially filled with water. The hot exhaust gas then passes throughair-to-water heat exchanger tubes 130, where heat from the hot exhaustgas is transferred to water in the water vessel 120. The exhaust gasthen enters an egress chamber 170, before being expelled from the boiler100 through an exhaust vent 150. In some cases, the vented exhaust gasis still hot, so some energy from the combustion process is not utilizedby the boiler 100. This results in a lower efficiency heating system.

In the pressurized boiler 100, the heated water is pumped directly fromthe water vessel 120 through a hot water outlet 190 and circulatedthrough hot water pipes, where the heat from the hot water is conveyedto warm the environment, for example by water filled radiators orradiant floor heating tubes. The water circulates through the heatingsystem, and then is returned to the water vessel in the boiler through acold water inlet 180. In a pressurized boiler the temperature of thereturn water may impact factors such as the efficiency of the boiler100.

The water used for space heating is typically heated to a temperature inexcess of the temperature needed for domestic hot water. Therefore, adomestic hot water coil 140 may circulate water through the water vessel120 of the boiler 100 for domestic hot water use. Note that the watercirculating in the domestic hot water system is typically separate fromthe water within the boiler water vessel: the domestic hot water isheated by circulating the domestic water through the domestic hot watercoil 140 within the boiler water vessel 120. Therefore, the domestic hotwater system may generally operate at lower pressures than the boilersystem.

Another type of heat exchanger is a plate heat exchanger, which may becomposed of multiple, thin, slightly-separated plates that have verylarge surface areas and liquid flow passages for heat transfer. Thisstacked-plate arrangement can be more effective, in a given space, thana similarly sized shell and tube heat exchanger.

A liquid heat exchanger typically forces a gas upwards through a showerof liquid, for example, water, and the liquid is then conveyed elsewherefor cooling. This is commonly used for cooling gases whilst alsoremoving certain impurities, thus solving two problems at once. Forexample, a liquid heat exchanger is used in espresso machines as anenergy-saving method of cooling super-heated water to be used in theextraction of espresso. However, transporting cool water to hot gassesin general requires a considerable amount of energy. Also, in somecircumstances, for example, a traditional boiler, the liquid heatexchanger is contained within a pressurized housing, to contain theexpansion of vapor as the water boils. The pressurized housing addssignificant cost, bulk and weight to the heat exchanger.

Pollutants may be in the form of solid particles, liquid droplets, orgases. In addition, they may be natural or man-made. Particulates,alternatively referred to as particulate matter (PM) or fine particles,may be particles of solid or liquid suspended in a gas. Activities suchas burning fossil fuels in vehicles, power plants and various industrialprocesses also generate significant amounts of particulates.

Several approaches are commonly used to capture particulates inpollution control devices by industry or transportation devices.Pollution control devices may either destroy contaminants or remove themfrom an exhaust stream before it is emitted into the atmosphere.Examples of particulate control devices include mechanical collectors,such as dust cyclones, electrostatic precipitators, baghouses andparticulate scrubbers.

An electrostatic precipitator (ESP), or electrostatic air cleaner is aparticulate collection device that removes particles from a flowing gas(such as air) using the force of an induced electrostatic charge.Electrostatic precipitators are filtration devices that minimally impedethe flow of gases through the device, and remove fine particulate mattersuch as dust and smoke from the air stream. Baghouses are designed tohandle heavy dust loads, a dust collector consists of a blower, dustfilter, a filter-cleaning system, and a dust receptacle or dust removalsystem (distinguished from air cleaners which utilize disposable filtersto remove the dust).

Particulate scrubbers, or wet scrubbers, include a variety of devicesthat remove pollutants from a furnace flue gas or from other gasstreams. In a wet scrubber, the polluted gas stream is brought intocontact with the scrubbing liquid, typically by spraying the gas streamwith the liquid, or by forcing the gas stream through a pool of liquid,so as to remove the pollutants. Examples of wet scrubbers include bafflespray scrubbers, cyclonic spray scrubbers, ejector venturi scrubbers,and mechanically aided scrubbers.

Spray towers or spray chambers generally consist of empty cylindricalvessels made of steel or plastic and nozzles that spray liquid into thevessels. The inlet gas stream usually enters the bottom of the tower andmoves upward, while liquid is sprayed downward from one or more levels.This flow of inlet gas and liquid in the opposite direction is calledcountercurrent flow. Countercurrent flow exposes the outlet gas with thelowest pollutant concentration to the freshest scrubbing liquid. Manynozzles are placed across the tower at different heights to spray thegas as it moves up through the tower. Reasons for using many nozzlesinclude maximizing the number of fine droplets impacting the pollutantparticles and providing a large surface area for absorbing gas.

Baffle spray scrubbers are similar to spray towers in design andoperation. However, in addition to using the energy provided by thespray nozzles, baffles are added to allow the gas stream to atomize someliquid as it passes over them. In a simple baffle scrubber system,liquid sprays capture pollutants and also remove collected particlesfrom the baffles. Adding baffles slightly increases the pressure drop ofthe system.

An ejector or venturi scrubber is an industrial pollution controldevice, usually installed on the exhaust flue gas stacks of largefurnaces, but may also be used on any number of other air exhaustsystems. An ejector venturi scrubber uses a preformed spray, like aspray tower. The difference is that only a single nozzle is used insteadof many nozzles in a spray tower. This nozzle operates at higherpressures and higher injection rates than those in most spray chambers.The high-pressure spray nozzle is aimed at the throat section of aventuri constriction. The ejector venturi is distinct among availablescrubbing systems since it may move the process gas without the aid of ablower or fan.

In addition to using liquid sprays or the exhaust stream, mechanicallyaided scrubbing systems may use a motor to supply energy. The motordrives paddles which, in turn, generate and introduce water dropletsinto gas for particle collection. Mechanically aided scrubbers have theadvantage of requiring less space than other scrubbers, but theiroverall power requirements tend to be higher than other scrubbers ofequivalent efficiency. Significant power losses may occur in driving thepaddles. Therefore, not all the power used is expended for gas-liquidcontact. Examples of mechanically aided scrubbers include centrifugalfan scrubbers and mechanically induced spray scrubbers. Disadvantages ofmechanically aided scrubbers include their generally high maintenancerequirements, low absorption efficiency, and high operating costs.

However, many of the particulate control solutions are energy useintensive, and do not attempt to re-claim energy from the waste gasses.Similarly, heat exchangers may not remove particulates from exhaust gas.Therefore, there is a need in the industry to address the shortcomingsdescribed above.

SUMMARY

Embodiments of the present invention provide a gas-to-liquid heat andgas particulate scrubber exchanger system and method. Generallydescribed in architecture, a first aspect of the present invention isdirected to a heat exchanger. The heat exchanger includes a reservoirchamber having a liquid reservoir and a gas channel in contact with theliquid reservoir. The gas channel has a gas ingress side and a gasegress end, with the gas egress end disposed substantially opposite thegas ingress end. The liquid reservoir is in communication with a liquidingress port and a liquid egress port.

The heat exchanger includes a rotating shaft having a first heatexchange surface in rigid rotational accompaniment with the rotatingshaft. The rotating shaft is disposed within the reservoir chamber suchthat the first heat exchange surface is partially submerged in theliquid reservoir and is partially within the gas channel. The rotatingshaft is oriented to at least partially span the reservoir chamber gaschannel from the gas ingress end to the gas egress end. Gas flows in agas flow direction from the gas ingress end to the gas egress end, andthe liquid flows in a liquid flow direction from the liquid ingress endto the liquid egress end.

Generally described in architecture, a second aspect of the presentinvention is directed to a device, including a housing, a reservoirchamber, a rotating shaft and a driver connected to the rotating shaft.The reservoir chamber is disposed within the housing, and includes aliquid reservoir and a gas channel in contact with the liquid reservoir.The gas channel includes a gas ingress end and a gas egress end, withthe gas egress end disposed substantially opposite the gas ingress end.

The rotating shaft includes a heat exchange surface disposed to rotatearound the rotating shaft in rigid accompaniment with the rotatingshaft. The rotating shaft is disposed within the reservoir chamber suchthat the heat exchange surface is partially submerged in the liquidreservoir and partially within the gas channel. The rotating shaft isoriented to span at least a portion of the reservoir chamber gas channelfrom the gas ingress end to the gas egress end. The driver connected tothe rotating shaft is configured to rotate the rotating shaft.

Generally described, a third aspect of the present invention is directedto a method for exchanging heat between a gas and a liquid. The methodincludes the steps of providing a reservoir chamber having a housing, aliquid reservoir and a gas channel in communication with the liquidreservoir and further in communication with the housing, the gas channelhaving a ingress end and an egress end, introducing a gas into the gaschannel ingress end, providing a rotating shaft at least partiallyspanning the reservoir chamber, providing a first heat exchange surfacedisposed upon the rotating shaft, the first heat exchange surfaceconfigured to rotate in rigid conformity with the rotating shaft,partially submerging the first heat exchange surface in the liquidreservoir, rotating the rotating shaft, thereby partially coating thefirst heat exchange surface with a liquid film, and expelling the gasfrom the gas channel egress end.

Generally described, a fourth aspect of the present invention isdirected to a method for removing particulates from a gas. The methodincludes the steps of drawing a gas having particulates through areservoir chamber partially filled with a liquid, within the reservoirchamber, rotating a first heat exchange surface partially submerged inthe liquid, wherein the first heat exchange surface has a rotation axisconfigured to rotate at least a portion of the heat exchange surfacethrough the liquid, partially coating the first heat exchange surface inthe liquid, introducing the gas to the first heat exchange surface inthe reservoir chamber, and collecting particulates from the gas in theliquid.

The method under the fourth aspect may further include the steps ofvaporizing the liquid partially coating the first heat exchange surface,thereby producing a vapor, and coalescing the particulates into thevapor. The method may also include the steps of, within the reservoirchamber, rotating a second heat exchange surface, wherein the secondheat exchange surface is partially submerged in the liquid, drawing thevapor through the reservoir chamber toward from the first heat exchangesurface toward the second heat exchange surface in a first direction,introducing the vapor to the second heat exchange surface, andcondensing the vapor upon the second heat exchange surface.

Other systems, methods and features of the present invention will be orbecome apparent to one having ordinary skill in the art upon examiningthe following drawings and detailed description. It is intended that allsuch additional systems, methods, and features be included in thisdescription, be within the scope of the present invention and protectedby the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprincipals of the invention.

FIG. 1 is a diagram of a heat exchanger within a prior art boiler.

FIG. 2 is a diagram of the first embodiment of a heat exchanger deployedwithin an atmospheric boiler.

FIG. 3 is a diagram of a second embodiment of a heat exchanger deployedwithin an atmospheric furnace.

FIG. 4 is a cutaway diagram of a third embodiment of a heat exchangerand/or gas particulate scrubber.

FIG. 5 is a is a non-cutaway diagram of a third embodiment of a heatexchanger and/or gas particulate scrubber.

FIG. 6 is a diagram of rotating heat exchange surfaces in isolation.

FIG. 7A is a diagram of a fourth embodiment of a heat exchanger and/orgas particulate scrubber.

FIG. 7B is a cutaway diagram of a fourth embodiment of a heat exchangerand/or gas particulate scrubber.

FIG. 8 is a flowchart of an exemplary method for exchanging heat betweena gas and a liquid.

FIG. 9 is a flowchart of an exemplary method for removing particulatesfrom a gas.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

Exemplary embodiments of a low pressure heat exchanger are presented,where gasses are introduced directly to liquid. The liquid is exposed tothe gasses as a film upon a series of rotating discs partially submergedin a reservoir. The liquid may vaporize and then re-condense onsubsequent discs, exchanging heat between the gas and the reservoirliquid. The heat exchanger liquid may collect particulate matter fromthe gas, thereby scrubbing particulates from the gas.

Hot Water Space Heating System

FIG. 2 shows a first embodiment of a heat exchanger deployed in anatmospheric space heater 200. Fuel combusts in a burner 210, and the hotexhaust gas is introduced to a reservoir chamber 225, the hot exhaustgas passing from the burner 210 to the reservoir chamber 225 through aburner exhaust vent 215. The burner 210 may burn several types of fuel,for example, but not limited to, oil, natural gas, wood, wood pellets,coal and propane. It should be noted that in general, within thisdocument a pressurized vessel refers to a vessel intended to withstandthe pressure of fluid expansion due to temperature/state changes, inaddition to static pressure, where the vessel must merely withstand thepressure of a fluid due to gravity and atmosphere at a fixedtemperature.

The liquid used in the first embodiment is water. The reservoir chamber225 is partially filled to a water line 205 with water. Unlike prior artboilers 100 (FIG. 1), the reservoir chamber 225 is not sealed or underpressure, but instead is unpressurized, having a vent such as exhaustgas vent 250 open to the exterior of the heater 200. Similarly, the airin the reservoir chamber 225 may be open to the burner exhaust vent 215,so that gas can pass freely between the burner 210 and the reservoirchamber 225.

A rotating shaft 265 is connected to a motor 270, so that the motor 270rotates the rotating shaft 265. A plurality of heat exchange surfaces,which are implemented as discs 260 in the first embodiment, are attachedto the rotating shaft 265 so that the rotating shaft 265 passessubstantially through the center of each disc 260. The discs 260 areaffixed to the rotating shaft 265 so that the discs 260 rotate in rigidaccompaniment with the rotating shaft 265. The rotating shaft 265 isdisposed above the water line 205 so that the rotating shaft issubstantially parallel to the water line 205, and the discs 260 arepartially submerged.

The discs 260 in the first embodiment are substantially circular, butthere is no objection to other shapes used as heat exchange surfaces,such as ovals, octagons or hexagons, for example. The heat exchangesurfaces need not be flat and may have irregular shapes, as increasedsurface area may assist in transference of heat between the gas and theliquid. For example, there is no objection to a fibrous material such assteel wool used as a heat exchange surface.

As the rotating shaft 265 rotates, the discs 260 turn through the water,so that the portion of the disc 260 that is submerged emerges from thewater with a thin film of water upon the surface of the disc 260. Thesurface of disc 260 may be textured or scored, so that the action ofrotating the discs draws more water from the reservoir. For example,there may be dimples, cuts, or slits in the discs 260 so the rotatingdiscs 260 pick up and disperse the water, and maintain a film of wateron the discs 260. In addition, the rotating discs 260 may introducedroplets of water into the air above the water line 205. The discs maybe rotating at a relatively slow speed to minimize energy usage, forexample, at approximately 150 RPM. Faster or slower disc rotation speedsare also possible. The discs 260 may be formed of a heat resistantmaterial such as plastics, stainless steel, or other metals.

While in preferred embodiments the discs 260 are coated with water byrotating them through a reservoir of water, there is no objectionalternative embodiments where discs 260 are coated with water by othermechanisms, for example, by spraying water on discs 260 with a spraynozzle, dripping water on discs 260, splashing water on the discs 260,brushing or sponging water on the discs 260, or other mechanisms. Thesemechanisms may also serve to apply water to other surfaces in additionto the discs 260 themselves, for example, the interior surface of thereservoir chamber 225.

An exhaust fan (not shown) draws airflow from the burner 210, throughthe burner exhaust vent 215, through an air passage in the reservoirchamber 225 above the water line 205, and out through the exhaust gasvent 250. The hot burner exhaust gas is drawn from the burner 210 intothe reservoir chamber 225, and introduced to the rotating discs 260.Note the motor 270 used to rotate the disc rotating shaft 265 may alsobe used to rotate the exhaust fan (not shown).

When the hot gas from the burner 210 encounters the film of water on thedisc 260 closest to the burner exhaust vent 215, the water evaporatesoff of the disc 260, forming water vapor and cooling the gas. The fandraws the then cooler burner exhaust gas and the water vapor toward thesecond disc 260, where the water vapor encounters the cooler water filmon the disc 260, causing at least a portion of the water vapor tore-condense, further cooling the vent exhaust gas while the re-condensedwater enters the reservoir chamber 225 as hot water. This process mayrepeat as the exhaust gas is drawn toward the exhaust gas vent 250 andthe exhaust gas is introduced to the water film on subsequent discs 260.In the first embodiment of the space heater, when the gas reaches theexhaust vent 250, the gas has generally been cooled to a temperatureslightly above the temperature of the water in the reservoir chamber225.

Since the water vapor is immediately re-condensed to hot water, it doesnot have to be maintained under pressure. By heating the water in anunpressurized, open boiler, the need for thick, heavy componentscompliant with industry standard codes and standards, such as ASME(American Society of Mechanical Engineers) BPVC (Boiler and PressureVessel Code), is reduced, as the water in the reservoir chamber 225 maybe heated to a temperature sufficient for space heating purposes, butstill significantly below boiling temperature. Therefore, the reservoirchamber may not need to withstand pressures of prior art boilers. As aresult, the materials used to construct the reservoir chamber 225 may bemuch lighter weight and less expensive than the materials used for priorart boilers. For example, the walls of the reservoir chamber may beconstructed of thin stainless steel, which may be structurally supportedby insulation, as the primary force upon the reservoir walls is from thewater in the reservoir chamber 225 under the force of gravity, ratherthan pressure generated by heating water into water vapor. In addition,the water in the reservoir chamber 225 may act to limit the temperatureof the reservoir chamber walls, further allow use of lighter weightmaterials by reducing the need for thick insulating metal walls.

Under the first embodiment, most of the heat from the burner exhaust gasis transferred directly to the water in the reservoir chamber 225. Theheated water in the reservoir chamber 225 may be used to heat externalwater sources for space heating and domestic hot water. For example, adomestic hot water coil 240 located in the reservoir chamber 225 belowthe water line 205 may be used to heat domestic hot water in a mannersimilar to prior art boilers 100 (FIG. 1).

Similarly, water may be introduced to a reservoir heat exchanger 230 toheat water for space heating purposes. Cold water may be introduced tothe reservoir heat exchanger 230 through cold water inlet 280, and thewater in the heat exchanger 230 may be heated by the water in thereservoir chamber 225 before exiting through a hot water outlet 290.Unlike traditional boiler heating systems, the return temperature of thewater does not significantly impact the performance of the heater. Forexample, water returning to a pressurized boiler at a temperature belowthe condensing point of water, typically on the order of 140° F., couldcause damage to the boiler. The reservoir heat exchanger 230 may be, forexample, a water-to-water heat exchanger, thereby deriving its heat fromthe heated water in the reservoir chamber. Or, the reservoir heatexchanger 230 may be partially submerged below the water line 205, sothat the water in the heat exchanger derives its heat in part from thewater in the reservoir chamber 225, and in part from exposure to exhaustgas from the burner 210.

While the space heater 200 may not operate under pressures in excess ofone standard atmosphere, the space water passing through the reservoirheat exchanger 230 may be under higher pressure than the water in thereservoir chamber 225. For example, the space water may be pressurizedto force water through pipes upward to higher floors of the buildingfrom where the space heater 200 is located. Therefore, the system forpumping and circulating the space hot water may be pressurized and thussubject to ASME codes or other similar codes and standards forpressurized vessels. The circulation system may be constructed fromheavier and more expensive materials to withstand the additionalpressure. However, the pressurized part of the space heater 200 mayrepresent a substantially smaller portion of the system than in priorart boilers, allowing the space heater to be constructed from lessexpensive materials, than materials used for a pressurized boiler.

Forced Hot Air System

FIG. 3 shows a second embodiment of a heat exchanger deployed within anatmospheric space heater 300. The second embodiment 200 is similar tothe first embodiment 300 in that both heaters have a burner 210 thatvents heated exhaust gas through a burner vent 215 into a reservoirchamber 225. An egress fan (not shown) draws exhaust from the burner 210through the reservoir chamber 225. The hot exhaust gas encounters waterfilm on discs 260 partially submerged below a water line 205, the discs260 rotating on a rotating shaft 265, driven by a motor 270. The hot gasvaporizes the film of water on the first disc 260 closest to the burnervent 215, cooling the exhaust gas and forming a mixture of exhaust gasand water vapor. Similarly, the hot gas may vaporize the film of wateron the second disc 260 and/or subsequent discs in the reservoir chamber.As the mixture of exhaust gas and water vapor is drawn through thereservoir chamber 225, the mixture encounters subsequent discs 260,where some of the water vapor is cooled, causing some of the water vaporto re-condense and enter the reservoir 225 as hot water.

It should be noted that while water vapor is recondensed within thereservoir chamber 225 in second embodiment, in alternative embodiments,the water vapor may be drawn from the reservoir chamber 225 to anexternal chamber (not shown), for example, a vapor-to-air heatexchanger, where the water vapor is recondensed in the external chamber(not shown). The recondensed water may be returned to the reservoirchamber 225, or the water in the reservoir chamber 225 may bereplenished by another water source.

In the second embodiment, a vent 250 provides a conduit for hot watervapor to a hot air heater 380. The hot water vapor passes through avapor-to-air heat exchanger 390, before exiting from a heat exchangervent 350. The air heated in the heat exchanger 390 may then be forcedthrough hot air conduits, as with a conventional hot air furnace. Aswith the first embodiment, a domestic hot water coil 240 may be exposedto the heated water in the reservoir 225.

Note that fewer discs 260 may be used for the second embodiment than thefirst embodiment, as the exhaust entering the air-to-vapor heatexchanger 390 may typically be hotter than the desirable temperature ofgas emitted from the exhaust gas vent 250 (FIG. 2) in the firstembodiment. Fewer discs 160 may therefore result in less cooling of theexhaust gas, and less heating of the water in the reservoir 225.

Particulate Removal and Ash Storage

In addition to providing direct heating of water in the reservoirchamber instead of indirectly heating the water in the chamber through aheat exchanger (prior art), the first embodiment space heater 200 (FIG.2) and the second embodiment space heater 300 (FIG. 3) may also removeparticulates from the burner 210 exhaust gas, for example, in a pelletburning system. The burner exhaust gas may carry fly ash into thereservoir chamber 225. As the exhaust gas encounters the water film onthe discs 260, as well as the water vapor produced as the exhaust gasevaporates the water film and the droplets of water introduced to theair by the rotating discs, the fly ash in the exhaust gas may combinewith the water. As the water vapor re-condenses, as described above, there-condensing water carries the fly ash into the water in the reservoirchamber. Over time, the ash may tend to settle to the bottom of thereservoir chamber 225, as a layer of ash 207. As the discs 260 rotate,any ash that may accumulate on the disc 260 surface above the water line205 is carried into the water, thus cleaning the discs.

As mentioned previously, prior art systems have used water pumpedthrough spray nozzles to remove particulates from burner exhaust gas.The pump systems require significantly more energy to operate than theamount of energy required to draw the air through the reservoir chamber225 and to rotate the discs 260. In addition, spray nozzles may becomeclogged with particulate matter, requiring either filtering of the wateror cleaning of the nozzles.

In addition to accumulating fly ash in the reservoir chamber, heavy ashfrom the burner 210 may also be deposited in the reservoir chamber,forming an ash-water slurry. The reservoir chamber 225 may accumulate asignificant amount of ash into the ash-water slurry before maintenanceis required. The reservoir may be maintained, for example, by annualreplacement of the water in the reservoir chamber 225. The ash-waterslurry may then be disposed of, or processed to harvest chemicals foruse in byproducts, for example, fertilizer, or a soil de-acidifyingagent.

Gas Particulate Scrubber

Under a third embodiment, the heat exchanger and particulate scrubbermay similarly be used to remove particulates and reclaim energy fromwaste gasses, for example, when used as a smokestack scrubber. FIG. 4shows a cutaway view of the third embodiment of a heat exchanger and/orparticulate scrubber 400.

A liquid reservoir chamber, or housing 410 encloses a liquid reservoirand a gas channel. Gas in the gas channel is in direct physical contactwith the liquid contained in the liquid reservoir. The housing 410 isshown as a cutaway view to partially display the interior of the housing410. The interior of the housing 410 not otherwise containing liquidforms the gas channel. It should be noted that the gas-liquid interfacewithin the housing 410 is not shown in FIG. 4 to more clearly show theother elements. Liquid may be added to the liquid reservoir through theliquid ingress port 420 (inlet), and liquid may be removed from theliquid reservoir through the liquid egress port 425 (outlet).

Liquid may flow through the housing 410, the liquid having a liquid flowdirection from the liquid ingress port 420 to the liquid egress port425. Similarly, gas may enter the gas channel of the housing 410 throughthe gas ingress port 430, and gas may exit the gas channel through thegas egress port 435. Gas may flow through the housing 410, the flowhaving a gas flow direction from the gas ingress port 430 to the gasegress port 435. It should be noted that while the gas flow direction iscounter to the liquid flow direction in the third embodiment, there isno objection to alternative embodiments where the gas flow directioncoincides with the liquid flow direction. Similarly, there is noobjection to fluid having a first flow rate and gas having a second flowrate through the heat exchanger, where the first flow direction isdifferent from the second flow direction.

A rotating shaft 440 may extend from the exterior of the housing 410,and pass through the interior of the housing 410. The rotating shaft 440may pass entirely through the housing 410 in two locations, or may onlypass through the housing 410 in one location. The rotating shaft 440 maypass through a bearing 450. In embodiments where the rotating shaft 440passes through the housing 410 in two locations, there may be twobearings 450. While the bearing 450 in the third embodiment is externalto the housing 410, there is no objection to the bearing 450 beinginternal to the housing 410 or for the bearing 450 to be integral withthe housing 410. The rotating shaft 440 may further be connected to adriver (not shown), such as a motor, to drive the rotating shaft 440.

Within the housing 410 one or more heat exchange surfaces, in thisembodiment shaped as discs 460, are attached to the rotating shaft 440such that each disc 460 rotates in rigid accompaniment with the rotatingshaft 450. A portion of each disc 460 is disposed within the liquid inthe liquid reservoir, and the remainder of each disc 460 is in the gaschannel. It may be desirable for up to half of each disc 460 be exposedto the gas channel. As the rotating shaft 440 rotates, each disc 460also rotates, such that the submerged portion of each disc 460 rotatesinto the gas channel, thereby drawing liquid from the liquid reservoirto be exposed to the gas in the gas channel as a liquid coating of thedisc 460. If the rotating shaft 440 is rotating quickly enough, therotation of the discs 460 may fling droplets of liquid into the gaschannel, some of which may spray against the interior of the housing410, where the liquid spray drops may coalesce and drip back into theliquid reservoir, or flow along the interior of the housing 410 backinto the liquid reservoir.

Each disc 460 may have one or more apertures 470, thereby facilitatingflow of gas through the gas channel and/or liquid through the liquidchannel. The apertures 470 may similarly facilitate the spraying actiondescribed above.

While discs 460 are generally flat and circular under the thirdembodiment, several variations in heat exchange surface shapes are alsopossible. For example, portions of each disc 460 may extend outward fromthe flat surface of the disc to facilitate the liquid spraying actiondescribed above. Similarly, the heat exchange surfaces may be shaped toassist in impelling gas through the gas channel and/or liquid throughthe liquid reservoir. In alternative embodiments, a drum (not pictured)may perform the heat exchange surface function of the disc 460. Further,there is no objection to having multiple heat exchange surfaces ofdifferent shapes and configuration within a single housing 410. Forexample, a first heat exchange surface 460 near the gas ingress port 430may be shaped to better facilitate evaporation of liquid, while a secondheat exchange surface 460 near the gas egress port 435 may be shaped tobetter facilitate coalescing of liquid.

FIG. 5 shows a non-cutaway view of the third embodiment of a heatexchanger and/or particulate scrubber 400, and FIG. 6 shows the rotatingheat exchange surfaces 460 in isolation on the rotating shaft 440. Otherembodiments within the scope of this disclosure include a housing 410where stationary baffles (not shown) are positioned between adjacentdiscs 460, in the liquid reservoir and/or in the gas channel.

While the housing 410 in the third embodiment is depicted in FIG. 4 assubstantially cylindrical in shape, having a circular cross section,there is no objection to configurations where the housing 410 isdifferently shaped, for example, having a rectangular cross section.

It may be desirable to monitor the level of liquid within the liquidreservoir, as condensation of additional liquid introduced to thehousing 410 as liquid vapor in the gas may add to the overall volume ofliquid in the system. Such additional liquid may then be purged from thesystem as needed.

Other variations may similarly be employed to remove particulates fromgas within the gas channel. Under one variation, an electrostatic chargemay be applied to one or more discs 460 to attract particulates in thegas that may be magnetically charged to the disc 460. Similarly, one ormore discharge electrodes may be disposed between heat exchangesurfaces, thereby imparting an electric charge to particulates in thegas and/or particulates collected within suspended liquid droplets. Suchcharged particles and/or droplets may then be attracted to collectingportions of the heat exchange surfaces in the gas channel, as per anelectrostatic precipitator (ESP). The particulates may thereafter beintroduced into the liquid reservoir as the collecting portions of theheat exchange surfaces rotate from the gas channel into the liquidreservoir.

In addition to advantages noted above, the third embodiment isadvantageous in that it is self-cleaning Particulates collected upondiscs 460 may be deposited from the disc 460 into the liquid reservoir.After the liquid is drawn from the liquid egress port 425, the liquidmay be filtered to remove the particulates from the liquid. Coatingrotating discs with fluid may consume less power than prior artmechanically aided scrubbers, as fluid generates less resistance to adisc rotating through fluid than, for example, a paddle pushing againstfluid.

It should be noted that there is no objection to the function of theliquid ingress port 420 and the liquid egress port 425 being reversed,such that the port 420 serves as an egress port or drain, and the port425 serves as an ingress port. It may be desirable for theingress/egress port 425 and/or the ingress/egress port 420 be placedtowards the bottom of the housing 410 in order to prevent buildup ofnon-liquid matter within the housing 410, for example, particulates.

In embodiments where water is used as the liquid, gas inlet temperaturesmay be in excess of 2000 degrees Fahrenheit. In such embodiments, hotgas will be converted to water vapor within a short distance from thegas ingress port 430. The rest of the distance between the gas ingressport 430 and the gas egress port 435 may generally function to condensethe water vapor to extract the energy, while simultaneously removingsignificant quantities of particulates, such as fly ash in exampleswhere combustion gasses are used.

FIGS. 7A and 7B show an exemplary fourth embodiment of a heat exchangerand/or particulate scrubber 700. The fourth embodiment is essentiallysimilar to the third embodiment, with the addition of an indirect heatexchange coil 783 that may be disposed within the housing 410. The heatexchange coil may function similarly to a traditional boiler, where coolwater enters an inlet 780 is heated by hot gasses and fluid as it passesthrough the housing 410, such that the water is warmer when it exits theheat exchanger 700 via an outlet 785. The heat exchange coil 783 may bepositioned such that is mostly within the liquid reservoir.Alternatively, heat exchange coil 783 may be positioned such that ismostly above the liquid reservoir, such that the heat exchange occursbetween the heated gas and the fluid within the heat exchange coil 783.As shown in FIG. 7B, the heat exchange coil 783 may be configured as ahelix largely along the outer wall of the housing 410. Of course, otherconfigurations of the indirect heat exchange coil 783 may also beconsidered within the scope of this disclosure. Note there is noobjection to reversing the function of the inlet 780 and the outlet 785,such that the cooler fluid enters near the gas inlet 440 and exits nearthe gas outlet 435.

Methods

FIG. 8 is a flowchart of an exemplary method for exchanging heat betweena gas and a liquid. It should be noted that any process descriptions orblocks in flow charts should be understood as representing modules,segments, portions of code, or steps that include one or moreinstructions for implementing specific logical functions in the process,and alternative implementations are included within the scope of thepresent invention in which functions may be executed out of order fromthat shown or discussed, including substantially concurrently or inreverse order, depending on the functionality involved, as would beunderstood by those reasonably skilled in the art of the presentinvention.

The method includes the step of providing a reservoir chamber with ahousing, a liquid reservoir and a gas channel, as shown by block 810. Arotating shaft spanning the reservoir chamber is provided with a heatexchange surface configured to rotate with the rotating shaft, as shownby block 820. The heat exchange surface is partially submerged in theliquid reservoir, as shown by block 830. The rotating shaft is rotated,thereby partially coating the heat exchange surface with a liquid film,as shown by block 840. Hot gas is introduced to the heat exchangesurface, as shown by block 850. The hot gas transfers heat to the liquidand vaporizes the liquid. Cooled gas is expelled from the gas channel,as shown by 860.

FIG. 9 is a flowchart of an exemplary method for removing particulatesfrom a gas. The method includes the step of drawing a gas comprisingparticulates through a reservoir chamber partially filled with a liquid,as shown by block 910. A heat exchange surface partially submerged inthe liquid is rotated within the reservoir chamber, rotating a firstheat exchange surface, as shown by block 920. The heat exchange surfaceis partially coated in the liquid, as shown by block 930. The gas isintroduced to the heat exchange surface in the reservoir chamber, asshown by block 940. The liquid coating the heat exchange surface isevaporated by the hot gas, and liquid droplet surround and encompassparticulates in the gas. Particulates from the gas are collected in theliquid, as shown by block 950.

In summary, an atmospheric, low maintenance heat exchange andparticulate scrubbing method, system and apparatus are presented.Instead of bringing gas to liquid, the liquid is introduce to hot gasusing partially submerged rotating heat exchange surfaces. Since theheat exchange occurs in an open, non-pressurized vessel, lighter andless expensive materials may be used compared with pressurized heatexchange systems.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncover modifications and variations of this invention provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A heat exchanger, comprising; a reservoir chamberconfigured to contain a liquid reservoir and a gas channel in contactwith said liquid reservoir, said reservoir chamber further comprising agas ingress end and a gas egress end, a liquid ingress port and a liquidegress port; and a rotating shaft comprising a first heat exchangesurface in rigid rotational accompaniment with said rotating shaft, saidrotating shaft disposed within said reservoir chamber such that saidfirst heat exchange surface is configured to be partially submerged insaid liquid reservoir and partially within said gas channel, saidrotating shaft oriented to at least partially span said reservoirchamber gas channel.
 2. The heat exchanger of claim 1, furthercomprising a driver configured to rotate said rotating shaft.
 3. Theheat exchanger of claim 1, further comprising a gas impeller incommunication with said reservoir chamber gas channel.
 4. The heatexchanger of claim 1, further comprising a liquid impeller incommunication with said liquid reservoir.
 5. The heat exchanger of claim1, further comprising: a driver connected to said rotating shaft suchthat said driver rotates said rotating shaft; and a gas impeller incommunication with said reservoir chamber gas channel, wherein saiddriver connected to said rotating shaft is further configured to drivesaid gas impeller.
 6. The heat exchanger of claim 1, wherein said firstheat exchange surface further comprises an aperture.
 7. The heatexchanger of claim 1, wherein said first heat exchange surface furthercomprises an impeller.
 8. The heat exchanger of claim 1, furthercomprising a second heat exchange surface in rigid rotationalaccompaniment with said rotating shaft, said second heat exchangesurface disposed substantially parallel to said first heat exchangesurface.
 9. The heat exchanger of claim 8, further comprising astationary baffle disposed substantially between said first heatexchange surface and said second heat exchange surface
 10. The heatexchanger of claim 1, wherein the first heat exchanger comprises asubstantially flat first disc.
 11. The heat exchanger of claim 1,further comprising an indirect heat exchange coil disposed within saidreservoir chamber, wherein said reservoir chamber further comprises aheat exchange coil inlet and a heat exchange coil outlet.
 12. A device,comprising; a housing; a reservoir chamber disposed within said housingconfigured to contain a liquid reservoir and a gas channel in contactwith said liquid reservoir, said reservoir chamber further comprising agas ingress end and a gas egress end; a rotating shaft comprising a heatexchange surface disposed to rotate around said rotating shaft in rigidaccompaniment with said rotating shaft, said rotating shaft disposedwithin said reservoir chamber, said rotating shaft oriented to span atleast a portion of said reservoir chamber gas channel; and a driverconnected to said rotating shaft, said driver configured to rotate saidrotating shaft.
 13. The device of claim 12, further comprising areservoir chamber gas channel impeller configured to impel gas into saidgas channel gas ingress end and expel gas from said gas channel gasegress end.
 14. The device of claim 12, further comprising a baffledisposed within said reservoir chamber gas channel.
 15. The device ofclaim 12, wherein said driver rotating shaft additionally configured todrive said gas channel egress impeller.
 16. The device of claim 12,further comprising an electrode configured to form an electric fieldwithin said gas channel.
 17. The device of claim 12, further comprisingan indirect heat exchange coil disposed within said reservoir chamber,wherein said reservoir chamber further comprises a heat exchange coilinlet and a heat exchange coil outlet.
 18. A method for exchanging heatbetween a gas and a liquid, comprising the steps of: providing areservoir chamber comprising a housing, a liquid reservoir and a gaschannel in communication with said liquid reservoir and further incommunication with said housing, said gas channel having a ingress endand an egress end; providing a rotating shaft at least partiallyspanning said reservoir chamber; providing a first heat exchange surfacedisposed upon said rotating shaft, said first heat exchange surfaceconfigured to rotate in rigid conformity with said rotating shaft;partially submerging said first heat exchange surface in said liquidreservoir; rotating said rotating shaft, thereby partially coating saidfirst heat exchange surface with a liquid film; and introducing a gasthrough said gas channel ingress end to said first heat exchangesurface; expelling said gas from said gas channel egress end.
 19. Themethod of claim 18, further comprising the step of flinging said liquidfrom said first heat exchange surface onto said housing.
 20. A methodfor removing particulates from a gas, comprising the steps of: drawing agas comprising particulates through a reservoir chamber partially filledwith a liquid; within said reservoir chamber, rotating a first heatexchange surface partially submerged in said liquid; partially coatingsaid first heat exchange surface in said liquid; introducing said gas tosaid first heat exchange surface in said reservoir chamber; andcollecting particulates from said gas in said liquid.
 21. The method ofclaim 20, further comprising the steps of: vaporizing said liquidpartially coating said first heat exchange surface, thereby producing avapor; and coalescing said particulates into said vapor.
 22. The methodof claim 21, further comprising the steps of: within said reservoirchamber, rotating a second heat exchange surface, wherein said secondheat exchange surface is partially submerged in said liquid; drawingsaid vapor through said reservoir chamber toward from said first heatexchange surface toward said second heat exchange surface in a firstdirection; introducing said vapor to said second heat exchange surface;and condensing said vapor upon said second heat exchange surface. 23.The method of claim 20, further comprising the step of imparting anelectrostatic charging of a first polarity to said particulates withinthe gas.
 24. The method of claim 23, further comprising the step ofelectrostatically charging said first heat exchange surface with asecond polarity.